The present invention relates to an apparatus for treating a porous, absorbent material with a foamable chemical composition.
The use of foamed chemical compositions, e.g. dye compositions, to treat various substrates, e.g. carpets, is a relatively new field. Prior to the advent of this type of technology, in conventional processes, e.g. dyeing processes, the fabric to be dyed is immersed in a bath containing the dyestuff and auxiliary components. After allowing sufficient time for the dyestuff to migrate into the fibers forming the fabric, the fabric is removed from the bath, dried, and then treated to fix the dyestuff on the fibers. In such processes, a large amount of water is absorbed from the bath by the fabric, requiring a substantial amount of energy to dry the fabric.
One approach to a solution of this problem has been to employ the chemical compositions in the form of a foam, drastically reducing the amount of water absorbed by the substrate to be treated. However, at present, processes involving aqueous foam generation require expensive machinery to produce foams having the stability which has been thought necessary to obtain satisfactorily treated substrates. Furthermore, in these processes, special applicators are used for depositing the generated foam onto the substrates to be treated.
For example, in general, U.S. Pat. No. 4,023,526 discloses the use of foam applicator heads, comprising a foam distribution chamber, a foam distribution plate, a foam application chamber, and a nozzle to apply the foam to the substrate; U.S. Pat. No. 3,762,860 discloses that the foam should be stable until subjected to elevated temperatures in the presence of a steam atmosphere; U.S. Pat. No. 4,099,913 also discloses that the foam should have sufficient stability to permit it to be pumped from the foam generator to the applicator nozzle; U.S. Pat. No. 4,118,526 indicates that the foam should undergo minimal change during a period from at least about 20 minutes, and up to 24 hours after formation; additional patents which disclose the use of various foamed chemical compositions to treat various substrates are U.S. Pat. No. 3,969,780, U.S. Pat. No. 3,954,404, U.S. Pat. No. 3,990,840 and German Pat. No. 2,713,841.
More specifically, U.S. Pat. No. 4,023,526 discloses a process wherein foam is formed in conventional commercially available foaming means, and conveyed to a foam applicator head. The equipment used to produce the foam is well known and many different types are commercially available. The foam generator usually consists of a mechanical agitator. Air or other gas is used to form the foam. The process can be used to treat textiles, non-woven material, paper, leather or wood.
U.S. Pat. No. 3,762,860 discloses a process wherein air or other gas is introduced into a dyestuff solution to form foam, the foam is applied to a fabric, and the fabric is steamed to break the foam and cause the dyestuff to migrate into the fibers. The air or other gas can be introduced into the dyestuff solution by means of foam generators well known in the art. The gas can be introduced beneath the surface of the solution, or the solution can be agitated and aerated. In the examples of this patent, a milkshake mixer is used to form the foam.
U.S. Pat. No. 3,969,780 discloses a process wherein a dye solution is introduced into a foam machine and mixed therein with air to form a foam. The foam is sent to an applicator means where it is applied to a carpet as the carpet is being advanced beneath the applicator means.
U.S. Pat. No. 4,099,913 discloses converting a treating composition to foam in equipment which is well known and commercially available and which generally consists of a mechanical agitator to mix air and the liquid composition. The foam is conveyed to a foam applicator nozzle where it is transferred to the surface of a textile.
U.S. Pat. No. 3,954,404 discloses a process wherein foam containing a dye is fed to a foam dye box, and a carpet is completely immersed in the foam as it travels through the dye box.
U.S. Pat. No. 4,118,526 discloses a process wherein a liquid composition is converted to foam by conventional procedures, after which the foam is coated onto a fabric. The foam is produced in a mixer, and the foam is then conveyed through a line to the fabric. The patent also discloses that the foam can be conveyed to the fabric by a pump, gravity, or by hand.
U.S. Pat. No. 3,990,840 discloses foaming a liquid dyebath by means of a gaseous propellant. The foam is then applied to a textile, being evenly distributed thereon by means of a doctor knife or a roll.
All of these patents involve the preparation of a foam in some type of enclosed vessel, ad then transferring the foam to the substrate to be treated. This requires the use of expensive foam generating machinery, and the need for chemicals to stabilize the foam.